Patella clamp and drill guide surgical instrument and method of use

ABSTRACT

An orthopaedic surgical instrument includes a patella drill guide having a first bracket, a second bracket coupled to the first bracket and moveable relative to the first bracket. The second bracket includes a drill plate having a plurality of guide holes defined therein.

This application claims priority under 35 U.S.C. §120 to U.S.application Ser. No. 13/538,086, which was filed on Jun. 29, 2012 andclaimed priority under 35 U.S.C. §119 to U.S. Provisional ApplicationSer. No. 61/503,419 entitled “PATELLA CLAMP AND DRILL GUIDE SURGICALINSTRUMENT,” which was filed on Jun. 30, 2011, the entirety of each ofwhich is incorporated herein by reference.

CROSS-REFERENCES TO RELATED U.S. PATENT APPLICATIONS

Cross-reference is made to U.S. Provisional Patent Application Ser. No.61/503,164 entitled “PATELLA DRILL GUIDE AND CLAMP ASSEMBLY” by AbrahamWright et al., and U.S. Design Patent Application Ser. No. 29/396,511entitled “PATELLA DRILL GUIDE AND CLAMP” by Abraham Wright et al., eachof which is assigned to the same assignee as the present application, isfiled concurrently herewith, and is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to orthopaedic surgicalinstruments and, more particularly, to patella surgical instruments.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.A typical knee prosthesis includes a tibial tray, a femoral component,and a polymer insert or bearing positioned between the tibial tray andthe femoral component. In some cases, the knee prosthesis may alsoinclude a prosthetic patella component, which is secured to a posteriorside of the patient's surgically-prepared patella. To secure theprosthetic component to the patella, an orthopaedic surgeon may resectthe posterior side of the patient's natural patella to prepare thenatural patella to receive the prosthetic component. In use, the patellaprosthetic component articulates with the patient's natural orprosthetic femur during extension and flexion of the patient's knee.

To facilitate the replacement of the natural joint with the kneeprosthesis, orthopaedic surgeons use a variety of orthopaedic surgicalinstruments such as, for example, cutting blocks, drill guides, millingguides, and other surgical instruments.

SUMMARY

According to one aspect of the disclosure, an orthopaedic surgicalinstrument is disclosed. The orthopaedic surgical instrument includes apatella drill guide that has a first bracket and a second bracketmoveably coupled to the first bracket, and a gasket that is removablycoupled to the second bracket. The second bracket includes a drill platehaving a plurality of guide holes defined therein, and the drill plateis formed from a substantially transparent material. Each of theplurality of guide holes is sized to receive a surgical drill. Thegasket is configured to cover the guide holes when coupled to the secondbracket.

In some embodiments, the first bracket may include a mounting plate. Themounting plate may have a first clamping surface with a first pluralityof teeth extending therefrom. The drill plate of the second bracket mayinclude a first clamping surface facing the first clamping surface ofthe mounting plate. The first clamping surface of the drill plate mayhave a second plurality of teeth extending therefrom.

In some embodiments, the first clamping surface of the mounting platemay extend substantially parallel to the first clamping surface of thedrill plate. Additionally, in some embodiments, the gasket may have afirst surface configured to contact the first clamping surface of thedrill plate. The first surface of the gasket may have a plurality ofpositioning holes defined therein that are configured to receive thesecond plurality of teeth of the drill plate. In some embodiments, thegasket may have a concave second surface opposite the first surface.

In some embodiments, the first clamping surface of the drill plate mayhave a plurality of etch marks defined therein. Each etch mark maycorrespond to a size of a patient's patella. Additionally, in someembodiments, the plurality of etch marks may be arranged as a pluralityof inscribed lines defined in the first clamping surface of the drillplate. In some embodiments, the drill plate may have a front surfacepositioned opposite the first clamping surface. Each inscribed line maybe visible through the front surface.

In some embodiments, the mounting plate and the drill plate may beformed from a polymeric material. In some embodiments, the orthopaedicsurgical instrument may include a plurality of metal bushings attachedto the drill plate. Each metal bushing may define a corresponding one ofthe plurality of guide holes.

Additionally, in some embodiments, the plurality of guide holes of thedrill plate may be arranged in a triangular pattern. In someembodiments, the gasket may be formed from an elastomeric material.

According to another aspect of the disclosure, an orthopaedic surgicalinstrument has a housing including a handle and a first bracket. Thefirst bracket has a mounting plate and a plurality of teeth extendingtherefrom. The orthopaedic surgical instrument also includes a secondbracket moveably coupled to the housing. The second bracket has a drillplate spaced apart from the mounting plate of the first bracket, and thedrill plate includes a plurality of guide holes. Each of the guide holesis sized to receive a surgical drill, and a plurality of teeth extendfrom the drill plate toward the mounting plate. The orthopaedic surgicalinstrument further includes a clamp actuation mechanism coupled to thehousing and the second bracket. The clamp actuation mechanism isoperable to move the second bracket in a first direction toward thefirst bracket.

In some embodiments, each of the plurality of guide holes may have alongitudinal axis extending therethrough. The second bracket may includea beam moveably coupled to the housing. The beam may be configured tomove relative to the housing along an axis extending parallel to thelongitudinal axes of the guide holes. Additionally, in some embodiments,the clamp actuation mechanism may include an actuation plate positionedin the housing and configured to engage the beam. The actuation platemay include a follower surface. The clamp actuation mechanism mayinclude a lever pivotally coupled to the housing such that the lever ismoveable between a first position and a second position. The lever mayinclude a cam surface configured to engage the follower surface of theactuation plate when the lever is moved from the first position to thesecond position such that the actuation plate engages the beam to movethe second bracket along the axis in the first direction.

In some embodiments, the clamp actuation mechanism may include a biasingelement positioned between the actuation plate and an inner wall of thehousing.

Additionally, in some embodiments, the orthopaedic surgical instrumentmay further include a locking mechanism configured to selectivelyprevent movement of the second bracket in a second direction away fromthe first bracket. In some embodiments, the locking mechanism mayinclude a locking plate moveable between a first position in which thelocking plate engages the beam to prevent movement of the second bracketin the second direction, and a second position in which the lockingplate is disengaged from the beam such that the second bracket ispermitted to move in the second direction. The locking mechanism mayinclude a biasing element positioned between the locking plate and thehousing. The biasing element may be configured to bias the locking platein the first position. In some embodiments, the orthopaedic surgicalinstrument may include a release button attached to the locking plate.

According to another aspect, the orthopaedic surgical instrumentincludes a polymeric housing including a handle and a first bracket. Thefirst bracket may have a mounting plate and a plurality of teethextending therefrom. The orthopaedic surgical instrument also includes asecond bracket moveably coupled to the housing. The second bracket has adrill plate formed from a substantially transparent material. The drillplate includes a clamping surface, a front surface, and a plurality ofguide holes extending through the clamping surface and the frontsurface. Each of the guide holes is sized to receive a surgical drill. Aplurality of etch marks are defined in the clamping surface of the drillplate. The plurality of etch marks are visible through the frontsurface. The orthopaedic surgical instrument further includes a clampactuation mechanism coupled to the polymeric housing and the secondbracket and a locking mechanism coupled to the housing and the secondbracket. The clamp actuation mechanism is operable to move the secondbracket in a first direction toward the first bracket, and the lockingmechanism is configured to selectively prevent movement of the secondbracket in a second direction away from the first bracket.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is a perspective view of an orthopaedic surgical instrument;

FIG. 2 is a rear elevation view of a drill plate of the orthopaedicsurgical instrument of FIG. 1;

FIG. 3 is a front elevation view of the drill plate of FIG. 2;

FIG. 4 is a partial cutaway side elevation view of the orthopaedicsurgical instrument of FIG. 1 showing the drill plate in one positionrelative to a housing of the orthopaedic surgical instrument;

FIG. 5 is a partial cutaway side elevation view of the orthopaedicsurgical instrument of FIG. 1 showing the drill plate in anotherposition relative to the housing;

FIG. 6 is a partial cutaway side elevation view similar to FIG. 5;

FIG. 7 is a partial cutaway side elevation view similar to FIGS. 5 and6;

FIG. 8 is a perspective view of a compression gasket of the orthopaedicsurgical instrument of FIG. 1;

FIG. 9 is a side elevation view of the orthopaedic surgical instrumentof FIG. 1 with a patient's resected patella and a prosthetic patellacomponent;

FIG. 10 is a front elevation view of the orthopaedic surgical instrumentof FIG. 1 with the patient's resected patella positioned between thedrill plate and a mounting plate of the orthopaedic surgical instrument;

FIG. 11 is a perspective view of the orthopaedic surgical instrument ofFIG. 1 with a surgical drill; and

FIG. 12 is a perspective view of the orthopaedic surgical instrument ofFIG. 1 with a patella prosthetic component secured to the patient'sresected patella.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthe specification in reference to the orthopaedic implants and surgicalinstruments described herein as well as in reference to the patient'snatural anatomy. Such terms have well-understood meanings in both thestudy of anatomy and the field of orthopaedics. Use of such anatomicalreference terms in the written description and claims is intended to beconsistent with their well-understood meanings unless noted otherwise.

Referring to FIG. 1, an orthopaedic surgical instrument 10 includes apatella clamp and drill guide 12 (hereinafter guide 12) and acompression gasket 14 configured to be secured to the guide 12. Asdescribed in greater detail below, the instrument 10 is utilized tosurgically prepare a patient's resected patella 16 (see FIG. 9) forimplantation of a patella prosthetic component, such as a patellaprosthetic component 18 (see FIG. 9). To do so, the patient's resectedpatella 16 may be positioned in the guide 12, and the surgeon may usethe guide 12 to drill fixation holes into the planar, resected posteriorsurface. The surgeon may also use the guide 12 to size and select apatella prosthetic component suitable for use with the particularpatient's patella. After the patella prosthetic component is selected,the surgeon may use the guide 12 and the gasket 14 to secure theselected patella prosthetic component to the patient's resected patella.

As shown in FIG. 1, the guide 12 of the instrument 10 includes a housing20 and a clamping bracket 22 configured to move relative to the housing20. The housing 20 has a main body 24 and a handle 26 extendingdownwardly from the main body 24. The handle 26 includes a plurality ofribs 28 that define a grip 30, which is sized to be grasped by a hand ofa surgeon. The housing 20 also includes a support bracket 32 thatextends from the main body 24 opposite the handle 26. The supportbracket 32 has a mounting plate 34 configured to engage the anteriorside of the patient's resected patella 16.

The clamping bracket 22 of the guide 12 includes a beam 36 and a drillplate 38 attached to the beam 36. The beam 36 is received in apassageway 40 defined in the main body 24 of the housing 20 and isconfigured to slide relative to the housing 20. The guide 12 also has aclamp actuation mechanism 42 that includes a lever or trigger arm 44extending downwardly from the main body 24 of the housing 20. Thetrigger arm 44 is configured to pivot relative to the housing 20 whenforce is applied as indicated by arrow 46. By operating the trigger arm44, the drill plate 38 of the clamping bracket 22 may be advanced towardthe mounting plate 34 of the support bracket 32, as described in greaterdetail below.

The beam 36 of the clamping bracket 22 extends outwardly from thepassageway 40 of the housing 20 to an end 50. A pair of mounting arms52, 54 extends upwardly from the end 50 of the beam 36, and the drillplate 38 is secured to the mounting arms 52, 54. In the illustrativeembodiment, the drill plate 38 and the beam 36 are formed separately andlater assembled. It should be appreciated that in other embodiments thebeam 36 and the drill plate 38 may be molded or otherwise formed as asingle monolithic component.

The drill plate 38 of the clamping bracket 22 has a planar clampingsurface 56 that faces the mounting plate 34, a front surface 58 oppositethe clamping surface 56, and a side wall 60 that connects the surfaces56, 58. A plurality of teeth 62 extend from the clamping surface 56toward the mounting plate 34 of the support bracket 32, and each tooth62 includes a tip 64 configured to engage the patient's resected patella16. As shown in FIG. 1, the drill plate 38 includes three teeth 62 thatare arranged in a triangular pattern on the clamping surface 56. Itshould be appreciated that in other embodiments the drill plate 38 mayinclude additional teeth or fewer teeth arranged in other geometricpatterns. Additionally, in other embodiments, the teeth may be removablyattached to the drill plate 38.

The drill plate 38 also includes a plurality of cylindrical openings 66extending through the surfaces 56, 58. The openings 66 are arranged in atriangular pattern, and each opening 66 has a bushing 68 positionedtherein. A guide hole 70 of the drill plate 38 is defined through eachbushing 68, and each guide hole 70 has a longitudinal axis 72 extendingtherethrough. As described in greater detail below, each guide hole 70is sized to receive a surgical drill 74 (see FIG. 11) and guide thedrill 74 along the axis 72 into contact with the patient's resectedpatella 16. In the illustrative embodiment, the drill plate 38 has threeguide holes 70. It should be appreciated that in other embodiments thedrill plate 38 may include additional or fewer guide holes 70 arrangedin a geometric patterns other than the triangular pattern shown in FIG.1.

The bushings 68 of the drill plate 38 are formed from a metallicmaterial such as stainless steel. In other embodiments, the bushings 68may be formed from a polymeric material resistant to wear. It shouldalso be appreciated that in other embodiments the bushings 68 may beomitted.

The housing 20 and the beam 36 of the clamping bracket 22 are eachformed from a polymeric material, such as, for example, polyethylene. Inother embodiments, the housing 20 and the beam 36 may be formed from ametallic material such as stainless steel. The drill plate 38 is formedfrom a substantially transparent material. In the illustrativeembodiment, the drill plate 38 is formed from an acrylate polymer, suchas, for example, polycarbonate. It should also be appreciated that thedrill plate 38 may be formed from other substantially transparentmaterial, such as, for example, methyl acrylate or glass.

Referring now to FIGS. 2 and 3, the drill plate 38 of the clampingbracket 22 includes multiple indicators 80 that correspond to multiplesizes of the patient's patella. The indicators 80 include a plurality ofetch marks 82 that are defined in the clamping surface 56, each of whichcorresponds to a different size of a patient's patella. As shown in FIG.2, the etch marks 82 are arranged as a number of inscribed lines 84 thatindicate narrow and intermediate sizes. The indicators 80 also includean outer circumference 86 of the side wall 60 of the drill plate 38,which indicates the widest patella size of the patella sizes indicatedby the indicators 80. In other embodiments, the drill plate 38 may belarger and include additional indicators 80 corresponding to otherpossible sizes of the patient's patella.

Each of the indicators 80 is identified by a corresponding numericalsymbol 88, which, in turn, corresponds to a particular patella size.When the indicators 80 are viewed as shown in FIG. 2, the numericalsymbols 88 appear backward or mirrored. When viewed as shown in FIG. 3,the etch marks 82 and the numerical symbols 88 are properly oriented andvisible through the front surface 58 because the drill plate 38 issubstantially transparent. Similarly, when a patient's resected patellais positioned between the drill plate 38 and the mounting plate 34, thepatella is also visible through the front surface 58. It should beappreciated that in other embodiments the lines and indicators may beformed on the plate 38 via printing or painting rather than by etching.

Referring now to FIGS. 4-7, the clamp actuation mechanism 42 of theguide 12 is shown in greater detail. As described above, the clampactuation mechanism 42 includes a trigger arm 44 that extends downwardlyfrom the main body 24 of the housing 20, and the trigger arm 44 may beoperated to move the clamping bracket 22 relative to the housing 20 inthe direction indicated by arrow 98. The trigger arm 44 has a body 100including a lower lever arm 102 positioned below the main body 24adjacent to the handle 26. The body 100 also includes an upper lever arm104 that is positioned within the main body 24 of the housing 20.

As shown in FIG. 4, the body 100 of the trigger arm 44 is attached tothe main body 24 via a joint 106. The joint 106 includes a cylindricalpin 108 positioned in a cylindrical opening 110 defined through the body100 and a pair of mounting holes (not shown) defined in the main body 24of the housing 20. In that way, the trigger arm 44 is configured topivot relative to the housing 20 between the extended position shown inFIG. 4 and the compressed position shown in FIG. 5.

The clamp actuation mechanism 42 also includes an actuation plate 112that has a front surface 114 and a rear surface 116. As shown in FIGS.4-7, the upper lever arm 104 of the trigger arm 44 includes a camsurface 118 that engages the front surface 114 of the actuation plate112. The clamp actuation mechanism 42 also includes a biasing element,such as, for example, a spring 120, which extends over the beam 36 ofthe clamping bracket 22 and is positioned between rear surface 116 ofthe actuation plate 112 and an inner wall 122 of the housing 20. Thespring 120 is configured to bias the clamp actuation mechanism 42 in theextended position shown in FIG. 4.

The actuation plate 112 of the clamp actuation mechanism 42 has a closedslot 124 extending through the surfaces 114, 116 of the plate 112. Asshown in FIG. 4, the actuation plate 112 is positioned over the beam 36,and the beam 36 extends through the slot 124. The slot 124 is defined byan inner wall 126 that extends between the surfaces 114, 116. The innerwall 126 of the actuation plate 112 includes a pair of engagement edges128, 130 that grip an upper surface 132 and a lower surface 134,respectively, of the beam 36.

The guide 12 of the instrument 10 also includes a locking mechanism 136that inhibits movement of the clamping bracket 22 relative to thehousing 20, including selectively preventing movement of the bracket 22in the direction indicated by arrow 138. The locking mechanism 136includes a locking plate 140 positioned in the main body 24 of thehousing 20 and a release button 142 attached to a lower end 144 of thelocking plate 140. The release button 142 includes a contoured frontsurface 146 and a rear surface 148 opposite the front surface 146. Thelocking mechanism 136 also includes a biasing element, such as, forexample, a spring 150 that is positioned between the rear surface 148 ofthe button 142 and an inner wall 152 of the housing 20.

An upper end 154 of the locking plate 140 is positioned in a slot 156defined between a pair of flanges 158 of the housing 20. The lockingplate 140, like the actuation plate 112, has a closed slot 160 extendingtherethrough. As shown in FIG. 4, the locking plate 140 is positionedover the beam 36, and the beam 36 extends through the slot 160. The slot160 is defined by an inner wall 162 having a pair of engagement edges164, 166 that grip the upper surface 132 and the lower surface 134,respectively, of the beam 36 to inhibit movement of the clamping bracket22 relative to the housing 20.

In use, the surgeon may utilize the clamp actuation mechanism 42 toadvance the drill plate 38 of the clamping bracket 22 toward themounting plate 34 of the support bracket 32. To do so, the surgeon orother user exerts a force on the lower lever arm 102 of the trigger arm44 in the direction indicated by arrow 46. The force is transferred fromthe trigger arm 44 to the actuation plate 112 through the engagement ofthe cam surface 118 of the upper lever arm 104 with the front surface114 of the actuation plate 112. As force is applied to the lower leverarm 102, the engagement edges 128, 130 of the actuation plate 112 gripthe upper surface 132 and the lower surface 134, respectively, of thebeam 36, and the actuation plate 112 pushes against the spring 120. Whena predetermined amount of force is applied to the trigger arm 44, theactuation plate 112 overcomes the bias of the spring 120 and the drillplate 38 advances toward the mounting plate 34 in the directionindicated by arrow 98.

As shown in FIGS. 4 and 5, the upper lever arm 104 of the trigger arm 44moves downward along the front surface 114 of the actuation plate 112 asthe trigger arm 44 pivots relative to the housing 20. The beam 36 of theclamping bracket 22 is drawn by the actuation plate 112 through thepassageway 40, moving along an axis 170 that extends parallel to thelongitudinal axes 72 defined by the guide holes 70 of the drill plate38. The movement of the clamping bracket 22 relative to the housing 20continues until the lower lever arm 102 of the trigger arm 44 contactsthe handle 26 in the compressed position shown in FIG. 5.

When the user releases the trigger arm 44, the removal of the forceexerted by the upper lever arm 104 causes the engagement edges 128, 130of the actuation plate 112 to disengage from the surface 132, 134,respectively, of the beam 36. The spring 120 urges the actuation plate112 to move in the direction indicated by arrow 172 while the clampingbracket 22 is held in position relative to the housing 20 by the lockingmechanism 136. The force exerted by the spring 120 is transferred fromthe actuation plate 112 to the trigger arm 44 through the engagement ofthe front surface 114 of the actuation plate 112 with the cam surface118 of the upper lever arm 104. The trigger arm 44 is thereby urged topivot relative to the housing 20 in the direction indicated by arrow 174and return to the extended position shown in FIG. 6.

In the extended position, the trigger arm 44 is prevented from pivotingfurther relative to the housing 20, and the actuation plate 112 islocked in position between the spring 120 and the upper lever arm 104.In that position, the engagement edges 128, 130 of the actuation plate112 grip the upper surface 132 and the lower surface 134, respectively,of the beam 36. The surgeon or user may repeat the steps outlined aboveto advance the drill plate 38 closer to the mounting plate 34.

When the surgeon or other user desires to move the drill plate 38 awayfrom the mounting plate 34, the surgeon may actuate the release button142 to release the locking mechanism 136, thereby permitting theclamping bracket 22 to move in the direction indicated by arrow 138, asshown in FIGS. 6 and 7. To do so, a predetermined amount of force isapplied to the contoured front surface 146 of the button 142 in thedirection indicated by arrow 168 to overcome the bias exerted by spring150. When a sufficient amount of force is applied, the locking plate 140tilts such that the engagement edges 164, 166 of the locking plate 140are released from the surfaces 132, 134 of the beam 36, as shown in FIG.7. The clamping bracket 22 may then be manually moved along the axis 170in the direction indicated by arrow 138 to any position relative to thehousing 20. The user is prevented from detaching the clamping bracket 22from the housing 20 by a stop 176 defined on an end 178 of the beam 36.When the clamping bracket 22 is located at the desired position, thebutton 142 may be released to re-engage the edges 164, 166 of thelocking plate 140 with the surfaces 132, 134 of the beam 36 and therebyprevent further movement of the clamping bracket 22 relative to thehousing 20.

Referring now to FIG. 8, the compression gasket 14 is shown in greaterdetail. The gasket 14 has a body 180 formed from an elastomeric materialsuch as rubber. It should be appreciated that in other embodiments thebody 180 may be formed from a polymeric material. The body 180 has aside surface 182 that is concave and is configured to receive a portionof the patella prosthetic component 18, as will be described in greaterdetail below.

The body 180 of the gasket 14 has another side surface 184 opposite theside surface 182. A plurality of mounting plugs 92 extend from the sidesurface 184. Each mounting plug 92 is sized to be received in acorresponding guide hole 70 of the drill plate 38. The body 180 also hasa plurality of holes 190 defined in the side surface 184 that are sizedto receive each of the teeth 62 extending from the clamping surface 56of the drill plate 38.

A tab 186 extends outwardly from the body 180 of the gasket 14. The tab186 includes a pair of contoured surfaces 188 configured to receive thefingertips of the user. In use, the user may grip the surfaces 188 tomove the gasket 14 relative to the drill plate 38, thereby moving thegasket 14 out of the drilling path when preparing to drill holes in apatient's resected patella. In that way, the plugs 92 of the gasket 14may be moved into and out of the guide holes 70 of the drill plate 38.

The mounting plugs 92 include a central plug 192 having a configurationthat substantially corresponds to the configuration of the centralaperture 94 of the drill plate 38. In particular, the central plug 192includes a trio of arms 194 that are sized and arranged to fit in thecorresponding trio of extension slots 96 of the aperture 94 such thatthe gasket 14 is attached to the drill plate 38 in a predeterminedorientation.

As described above, the guide 12 may be utilized to surgically prepare apatient's resected patella 16 for implantation of a patella prostheticcomponent 18, as shown in FIGS. 9-12. To do so, the surgeon may positionthe resected patella 16 between the mounting plate 34 and the drillplate 38 of the guide 12 with the compression gasket 14 decoupled fromthe guide 12. As shown in FIG. 9, the patient's resected patella 16 maybe positioned between the plates 34, 38 such that an anterior surface200 of the resected patella 16 faces a planar clamping surface 202 ofthe mounting plate 34 and a resected posterior surface 204 of theresected patella 16 faces the planar clamping surface 56 of the drillplate 38.

The planar clamping surface 202 of the mounting plate 34 extendsparallel to the planar clamping surface 56 of the drill plate 38 andincludes a plurality of teeth 206 extending therefrom. When thepatient's resected patella 16 is positioned between the plates 34, 38,the surgeon may move the anterior surface 200 of the patient's resectedpatella 16 into contact with the plurality of teeth 206 of the planarclamping surface 202. The surgeon may also clamp the patient's resectedpatella 16 between the plates 34, 38 by operating the clamp actuationmechanism 42 as described above to advance the drill plate 38 toward themounting plate 34.

Additionally, the surgeon may use the guide 12 to select a patellaprosthetic component. As shown in FIG. 10, the outer margin 208 of thepatient's resected patella 16 falls within one of the indicators 80,which corresponds to a particular size. Using the indicators 80, thesurgeon may select a patella prosthetic component that offers themaximum coverage of the resected posterior surface 204 of the resectedpatella 16.

After the surgeon has clamped the patient's resected patella 16 betweenthe plates 34, 38 of the guide 12, the resected posterior surface 204 ofthe patella 16 is surgically-prepared to receive the patella prostheticcomponent 18. As shown in FIG. 11, the surgeon may drill a series ofpilot holes in the surface 204 that correspond to the position of anumber of mounting pegs 210 of the component 18. To do so, the surgeonmay insert a surgical drill 74 into each of the guide holes 70 definedin the drill plate 38. The drill 74 is advanced along the axis 72through the guide hole 70 and into contact the surface 204. The surgeonactivates the drill 74 and advances the drill 74 along the guide hole 70until a pilot hole of sufficient depth is formed in the patient'sresected patella 16. The surgeon may then repeat the drilling operationthrough each of the guide holes 70 until the required pilot holes arecreated. At any time, the surgeon may actuate the release button 142 andmanually unclamp the patient's resected patella 16.

After pilot holes are created in the resected posterior surface 204, thesurgeon may position the patella prosthetic component 18 for attachmentto the patient's resected patella 16 and apply cement to the anteriorsurface 212 of the component 18. After the component 18 is positionedover the patient's resected patella 16, the pegs 210 may be advancedinto the pilot holes formed in the resected posterior surface 204 untilthe anterior surface 212 is placed into contact with the surface 204.The compression gasket 14 may be attached to the drill plate 38, therebycovering the teeth 62 extending outwardly from the clamping surface 56.In that position, the gasket 14 is positioned between the drill plate 38and the component 18.

The surgeon may again operate the clamp actuation mechanism 42 to clampthe component 18 to the patient's resected patella 16, as shown in FIG.12. To do so, the surgeon may squeeze the lower lever arm 102 to apply apredetermined amount of force to the trigger arm 44 to move the drillplate 38 and gasket 14 toward the mounting plate 34. The compressiongasket 14 is advanced into contact with the posterior bearing surface214 of the component 18, and the component 18 is seated within andstabilized by the concave surface 182 of the gasket 14 such that thecomponent 18 is clamped firmly to the patient's resected patella 16until polymerization is complete and the component 18 is secured to thepatient's resected patella 16.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected. For example, thegasket 14 may be omitted from embodiments of the instrument 10 where,for example, the teeth of the drill guide are removable or omitted.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

The invention claimed is:
 1. An orthopaedic surgical instrument,comprising: a patella drill guide that comprises (i) a first bracket and(ii) a second bracket moveably coupled to the first bracket, the secondbracket including a drill plate having a plurality of guide holesdefined therein, each of the plurality of guide holes being sized toreceive a surgical drill, and a gasket removably coupled to the secondbracket, the gasket having (i) a body configured to cover the pluralityof guide holes when the gasket is coupled to the second bracket and (ii)a plurality of pegs, each peg being sized to be received in each guidehole when the gasket is coupled to the second bracket, wherein the drillplate is formed from a substantially transparent material, and whereinthe plurality of guide holes of the drill plate are arranged in atriangular pattern, and the body has a concave surface configured toreceive a portion of a patella prosthetic component when the gasket iscoupled to the second bracket.
 2. The orthopaedic surgical instrument ofclaim 1, wherein: the first bracket includes a mounting plate, themounting plate having a first clamping surface with a first plurality ofteeth extending therefrom, and the drill plate of the second bracketincludes a first clamping surface facing the first clamping surface ofthe mounting plate, the first clamping surface of the drill plate havinga second plurality of teeth extending therefrom.
 3. The orthopaedicsurgical instrument of claim 2, wherein the first clamping surface ofthe mounting plate extends substantially parallel to the first clampingsurface of the drill plate.
 4. The orthopaedic surgical instrument ofclaim 2, wherein the gasket has a first surface configured to contactthe first clamping surface of the drill plate, the first surface of thegasket having a plurality of positioning holes defined therein that areconfigured to receive the second plurality of teeth of the drill plate.5. The orthopaedic surgical instrument of claim 4, wherein the concavesurface is opposite the first surface.
 6. The orthopaedic surgicalinstrument of claim 2, wherein the first clamping surface of the drillplate has a plurality of etch marks defined therein, each etch markcorresponding to a size of a patient's patella.
 7. The orthopaedicsurgical instrument of claim 6, wherein the plurality of etch marks arearranged as a plurality of inscribed lines defined in the first clampingsurface of the drill plate.
 8. The orthopaedic surgical instrument ofclaim 7, wherein the drill plate has a front surface positioned oppositethe first clamping surface, and each inscribed line is visible throughthe front surface.
 9. The orthopaedic surgical instrument of claim 2,wherein the mounting plate and the drill plate are formed from apolymeric material.
 10. The orthopaedic surgical instrument of claim 9,further comprising a plurality of metal bushings attached to the drillplate, each metal bushing defining a corresponding one of the pluralityof guide holes.
 11. The orthopaedic surgical instrument of claim 1,wherein the gasket is formed from an elastomeric material.
 12. Anorthopaedic surgical instrument, comprising: a housing including ahandle and a first bracket, the first bracket having a mounting plateand a plurality of teeth extending therefrom, a second bracket moveablycoupled to the housing, the second bracket having (i) a drill platespaced apart from the mounting plate of the first bracket and includinga plurality of guide holes, each of the guide holes being sized toreceive a surgical drill, and (ii) a plurality of teeth extending fromthe drill plate toward the mounting plate, a clamp actuation mechanismcoupled to the housing and the second bracket, the clamp actuationmechanism being operable to move the second bracket in a first directiontoward the first bracket, wherein (i) each of the plurality of guideholes has a longitudinal axis extending therethrough, and (ii) thesecond bracket includes a beam moveably coupled to the housing, the beambeing configured to move relative to the housing along an axis extendingparallel to the longitudinal axes of the guide holes, and a lockingmechanism configured to selectively prevent movement of the secondbracket in a second direction away from the first bracket, the lockingmechanism including (a) a locking plate moveable between (i) a firstposition in which the locking plate engages the beam to prevent movementof the second bracket in the second direction, and (ii) a secondposition in which the locking plate is disengaged from the beam suchthat the second bracket is permitted to move in the second direction,and (b) a biasing element positioned between the locking plate and thehousing, the biasing element biasing the locking plate in the firstposition.
 13. The orthopaedic surgical instrument of claim 12, whereinthe clamp actuation mechanism includes (i) an actuation plate positionedin the housing and configured to engage the beam, the actuation plateincluding a follower surface, and (ii) a lever pivotally coupled to thehousing such that the lever is moveable between a first position and asecond position, the lever including a cam surface configured to engagethe follower surface of the actuation plate when the lever is moved fromthe first position to the second position such that the actuation plateengages the beam to move the second bracket along the axis in the firstdirection.
 14. The orthopaedic surgical instrument of claim 13, whereinthe clamp actuation mechanism includes a biasing element positionedbetween the actuation plate and an inner wall of the housing.
 15. Theorthopaedic surgical instrument of claim 12, further comprising arelease button attached to the locking plate.